// Problem: 
// Contest: 
// URL: 
// Memory Limit: 
// Time Limit: 
// #pragma GCC optimize("Ofast")
// #pragma GCC optimize("unroll-loops")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
#include<bits/stdc++.h>
using namespace std;
#define int long long
inline int read(){
	int s=0,w=1;
	char ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-')w=-1;ch=getchar();}
	while(ch>='0'&&ch<='9') s=s*10+ch-'0',ch=getchar();
	return s*w;
}
signed main()
{
	int t=1;
	cin>>t;
	while(t--)
	{
		int a,b;
		cin>>a>>b;
		int ta=a,tb=b;
		a=max(ta,tb);
		b=min(ta,tb);
		if(a==b)cout<<1<<endl<<a<<endl;
		else
		{
			if(a%b!=0)cout<<-1<<endl;
			else 
			{
				cout<<2<<endl;
				cout<<b<<" "<<a-b<<endl;
			}
		}
	}
	return 0;
}
